1. Field of the Invention
The present invention relates to a feed horn device. More particularly, the present invention relates to an integrated feed horn device for receiving satellite signals transmitted from three satellites separated by small angles.
2. Description of Related Art
Recently, as the space technology advances, satellites are adopted for signal transmission. Since the coverage area for signal transmission via the satellite is very broad and the propagation path thereof is not easily influenced by the topography of the receiver, the satellite communication technology has gradually become the main stream of the communication technology. In general, the purpose of satellite is very broad and may be applied in, for example, military, meteorology, direct broadcast program and internet, wherein satellite direct broadcast system and internet are very suitable for household requirement. Therefore, the development of domestic satellite antenna has become more important and popular.
In general, synchronous satellite orbits the earth synchronously with the rotation of the earth. Therefore, the satellite may be provided as a relay station for signal transmission when the transmitters on the ground transmit signals between each other via the satellite. The signal is carried by radio wave transmitted from the transmitter to the satellite, and then the satellite transmits the signal which is carried by another radio wave, which is received by a parabolic reflector antenna of a receiver device on the ground.
For example, in the United States of America, the image signal of the satellite direct broadcast program carried by a circular polarization wave is transmitted to the viewer via the DBS satellite in longitude 119° W recently. In addition, the two-way transmission of the internet signal is performed via the FSS satellite in longitude 116.8° W, wherein the radio wave used to carry the internet signal is a linear polarization wave. Thus, the angle between these two satellites is very small (about 2.2°). Therefore, the feed angle of the two signals is very close. Generally, the satellite direct broadcast program and internet are the most popular household communication source of external information. Conventionally, an integrated feed horn device that can receive two radio waves from two satellites separated with a small angle has been developed, wherein two sets of feed horn devices are integrated in a single parabolic reflector antenna. Therefore, two conventional parabolic reflector antennas may be instead with a feed horn device to receive two signals from two satellites.
However, as the requirement of information communication advances, the amount of the satellites increased rapidly, therefore, the angle between every satellites are reduced rapidly. In addition, the receiver device is required to simultaneously receive a plurality of signals of every satellite. Presently, a receiver device is not capable of receiving three signals from three satellites separated by small angles since the angles between every satellites are small so that the intervals between every feed horn devices for each satellite is small. Therefore, three sets of conventional feed horn devices can not be integrated in a single parabolic reflector antenna to simultaneously receive three signals, and thus three parabolic reflector antennas are required for simultaneously receiving three signals from three satellites respectively. Thus, the conventional technology is not only expensive but also the plurality of parabolic reflector antennas occupies a large space.